With respect to fin field-effect transistor (FinFET) devices, bulk substrates, when compared to silicon-on-insulator (SOI) substrates, offer low cost. However, manufacturing a FinFET device on a bulk substrate may lead to variations in fin height and difficulties in controlling device characteristics. On the other hand, SOI substrates can provide little or no variation in fin height and good control and isolation, but are higher in cost when compared with bulk substrates.
With known methods of manufacturing a FinFET device using a bulk substrate, an insulator height, more specifically, a height of a shallow trench isolation (STI) region, defines fin height since the dielectric for the STI region is deposited on the substrate around the formed fins, recessing a bottom portion of each fin. As a result, unwanted device variability, including variations in the electrical characteristics of a device due to the fin height and difficulties isolating the fins, can occur. In contrast, SOI fins are formed on an existing buried dielectric region located below the resulting fins, and therefore STI thickness, when using an SOI substrate, will not significantly change fin height or result in unwanted device variability.